This invention relates to a medical securement element with a self-tapping screw thread, subdivided by cut-out notches into thread segments, which engages a counterpart thread in a bone.
A known securement element of this kind (German Offenlegungsschrift No. 2,340,546, British Patent Application No. 28426/74), U.S. Pat. No. 3,987,499 consists of an enamelled anchoring part with a self-tapping external rounded screw thread. The anchoring part includes axially parallel through-going cut-out notches for the removal of bone chips and is screwed into the appropriate bone with a tool, such as a box spanner, by means of lateral surfaces. One disadvantage of this anchoring part is that it seeks the path of least resistance when being screwed in and can follow the soft tissue in the bone. As a result, the end position of the anchoring part is not defined accurately and its threads turns are finally located in the least load-bearing bone tissue. Another disadvantage is that the torque required for screwing this anchoring part into the bone is relatively high.